Koka Castles

The 53 Koka Families 甲賀五十三家[edit]

The 53 clans of Koka ruled their territory semi-autonomously in a collective known as the Kokagunchuso (甲賀郡中惣). Each of the Koka family had roughly similar sized landholdings and each had an equal voice in governing the Koka lands. There were no vast territories or subservient hierarchy to give rise to large scale castles either. They relied on each other for a unified defense and built many small castles around their territories to effectively create one giant impenetrable castle network with a nearly uncountable number of defensive positions. Within the 53 Families there were also sub-groups of families with the same name such as the Wada Castle that managed local affairs on a smaller level. Some books or articles that briefly talk about the Koka region claim it to be subservient to the Rokkaku at Kannonji Castle. While some Koka samurai did serve as retainers to the Rokkaku at times, the Kokagunchuso collective considered themselves independent and important allies to the Rokkaku. You may have heard the term 'Koka Ninja' before. The origin of the Koka Ninja is deeply rooted in the history of these 53 families as highlighted in the history section below.

The Castles of Koka 甲賀の城郭網[edit]

Over 300 castles and fortified homes (yakata) were built across these lands. Some of these castles have been lost to time but traces of the original castle, either above ground or uncovered through archeological surveys, have been identified for around 180, the highest concentration of castles anywhere in Japan. If anyone tried to invade the lands they would have to take each castle one at a time slowly moving inward. If you ignored any one fortification (or didn't realize it was there!) you would run the risk of it being used to attack you from behind. This defensive collective and castle network was the only one of it's kind in Japan. During Hideyoshi's Korean Campaigns when they had penetrated to the Orangai Jurchen territories of Hamgyeong, Kato Kiyomasa commented in one of his writings that it was slow going because they had to take and fortify one village at a time. It reminded him of the Koka Region.

This was possible because of the unique and roughly flat societal structure of the Koka Samurai Alliance. (where to put this line?)

yakatajiro 館城[edit]

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The castles of the koka samurai primarily fall into the category of "single bailey" (単郭方形　たんかくほうけい) castles and more specifically (単郭方形四方土塁たんかくほうけいしほうどるい). In other words, square single bailey castles with earthen embankments on 4 sides. The typical castle has a main bailey roughly 30-50 meters square. Some of the biggest ones at Mochizuki Castle and Shingu Castle have embankments over 8 meters high. This puts them on a comparable scale to the biggest dorui (embankments) at places like Obata-jo and Ushiku-jo in Ibaraki or some of the biggest horikiri trenches of mountaintop castles. Similar "single bailey" (単郭方形) castles exist around the country but tend to be the much smaller fortified residences (yakata) of local lords and landholders. Koka and Iga are unique in that they are the only places where this design was scaled up to this "castle level", not simply a yakata. For this reason they are sometimes called yakatajiro (館城) to highlight their origins but emphasize that they are the scale of castles, not simple yakata. Despite their comparatively smaller size, the amount of organization and construction required to build and maintain this number of castles meets or exceeds the requirements of many larger castles of the time.

Shimoyama Castle is considered to be the ideal example of a preserved Koka Castle that most closely retains the original square yakatajiro structure. The site is easy to get to and well maintained making it a perfect place to kick off your exploration of Koka castles and to compare with others that you may visit. The additional baileys of Shimoyama Castle, really just leveled open spaces outside the main castle, seem almost like an afterthought or convenience rather than a planned part of the castle and have no particular defenses of their own such as embankments on the outer sides or trenches. From this basic yakatajiro design, the Koka castles were expanded with additional layers of smaller baileys and trenches around the outside for further fortification. Some of the best examples are to be seen at Shingu Castle, Mochizuki Castle and Wada Castle. These castles in particular may have been expanded even beyond typical measures because of the roles they played in the greater historical events of the time (see history below).

I would note one other difference that is not necessarily highlighted in the literature but is obvious after visiting many Koka castles. Some of the bigger yakatajiro on mountains or hillsides actually seem to have been carved from the mountain, rather than piling up earth to create embankments. Even Shimoyama Castle fits into this category. It is really a large hill, but one long trench (horikiri, yokobori, tatebori) separates the castle area from the non castle area. The interior of the castle that would be considered the honmaru has been carved out so the base is actually at a lower elevation and the surrounding walls which are what's left behind from the mountain. Certainly those on flatter lands were built in the more traditional yakata way but for those that have been carved out from the mountain it also offers a much greater variety in extra fortifications that allow castles to take advantage of elevation and topographical features of the location. One feature that intrigued me at several sites was a kind of long defensible obikuruwa or dorui type wall outside the honmaru. Shingu Castle and Mochizukishi Castle are great examples. There is the long Ninokuruwa bailey at Ueno Castle where it seems to shield or hide the castle behind it.

Mountain Castles of Koka 甲賀の山城[edit]

Along the borders of the Koka region you will also find some more traditional mountaintop castles which acted as lookouts and helped to fortify the borders. Mikumo Castle which sits at the entrance of Koka is a great example. Also, the castles of the Umasugi on the western border and those of the Horikita on the Eastern border in particular fall into this category but I don't have any to share yet. One theory I read said that due to the extreme importance of the Okka region to the Rokkaky they advised or influenced the development of these mountaintop fortressses to help protect the borders.

Map of Koka Castles 甲賀の城地図[edit]

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Several of the best Koka castle sites were designated "National Historic Sites of the Kokagunchuso" in 2008 and are well maintained including Shingu Castle, Shingushi Castle, Jizen Castle, Murasame Castle and Takenaka Castle. The other profiles you see here tend to focus on those that have more ruins to see. Many of the smaller sites are on private property and not specially preserved nor open to visitors casually walking through. In fact, some are so overgrown it may be difficult to find an entrance or move around to see the ruins (e.g. Shimoyamakita Castle) through the forest. Those that were located on plains or in more populated areas tend to have been completely developed over and have nothing to see. I visited a few that have become factories or farm fields, but they are not documented here simply because there was nothing to see or it is hidden behind a walled compound (lists...). For those on private property, be respectful and ask permission where practical. I was actually declined at one where the farmer was outside in his field (), which is why you only see one photo from a distance but the property owner of another (Uchikoshi Castle) was very knowledgable, a retired teacher, a member of the local ninja tourism association. we had a great chat along with his personal tour of the site. He also provided some tips for future travels and reiterated the point about private properties.

Koka samurai in history 歴史で見る甲賀侍[edit]

The 53 Koka Families allied themselves with the Sasaki Rokkaku. A few of the local samurai were employed by the Rokkaku but the region was not subservient to them. The Koka Families kept their distance and considered themselves allies. When the Rokkaku were attacked by the Ashikaga Shogun (Yoshihisa) in 1487 for resisting Ashikaga rule (Oumi Magari no Jin) Rokkaku Takayori himself holed up in Koka instead of Kannonji Castle. The guerilla warfare employed by the Koka samurai helped withstand the Ashikaga for 3 years until the shogun died and the Ashikaga relented. The Koka samurai again supported 5 yrs later the Rokkaku in another siege by the Ashikaga (1495 - NEED TO CHECK).

The Koka samurai's skill at guerilla warfare during this conflict earned them much notoriety and is the origin of the "Koka Ninja". It is from this time that local samurai started to be hired out as spies rather than make a meager living off the lands. They were not actually called Ninja at the time, they were called shinobi or Koka samurai. The Koka region of Shiga was well known for medicinal herbs so the Koka spies specialized in disguising themselves as medicine sellers while traveling. Medicine sellers had access to a wide range of classes of people, thus extending their reach for gathering information. Medicine sellers often travelled far and wide collecting herbs, so they could easily justify their travels, the perfect disguise. See also mochizuki residence…

In 1565 when future shogun Ashikaga Yoshiaki fled Nara (Kofukuji Ichijoin) ahead of Miyoshi forces that killed his brother Yoshiteru, it was Wada Koremasa, head of the Wada Koka Samurai, who helped him escape Nara and sheltered him at (his home . Koremasa went on to become an important messenger between Yoshiaki and Nobunaga and was granted Takatsuki Castle.

Finally, when Nobunaga started to assail Rokkaku territories (1568-1573) Rokkaku Yoshikata again fled to the Koka region. He found refuge with the MIkumo Castle and Mochizuki Castle after the fall of Kannnonji Castle and hid out in the Sugitani/Niiharu Castle network (Mochizuki Castle, Mochizukishi Castle. Shingu Castle, Shingushi Castle, Jizen Castle, Murasame Castle, Sugitani Castle, etc). Mochizuki also helped to secure an escape route for the Rokkaku through his allies in Iga. One theory said that the reason the Rokkaku were finally defeated by Nobunaga is because the allegiance of some of the Koka samurai (Wada and allies?) was won over by Tokugawa Ieyasu who influenced them not to interfere.

The events surrounding the fall of the Rokkaku and the rise of Oda Nobunaga caused the tightly knit Koka Alliance to start to crumble. Following the Honnoji Incident some Koka samurai (including the Wada Castle) helped Tokugawa Ieyasu escape through Koka and Iga. They were rewarded with the rank of Hatamoto and fought by his side in The Battle of Komaki & Nagakute against Hideyoshi. The allied families of Koka represented everything Hideyoshi was against. They were local farmer/samurai, they allied with Tokugawa, and the Koka Alliance was a direct threat to his centralized totalitarian rule. Hideyoshi oppressed Koka, confiscated territories, and reassigned samurai. He also built Minakuchi Okayama Castle at the entrance to the Koka region to exert his power and control. The Koka samurai were considerably weakened under Hideyoshi but they also regained some of their status with Tokugawa Ieyasu. They were effectively deployed for espionage during the Battle of Sekigahara. At the Battle of Fushimi Castle, the Koka samurai suffered devastating losses. For their great service, Tokugawa formed 100 small groups in Koka from the survivors and their families. Around 30 years later he moved them to Aoyama in Tokyo where they became trusted guards of Edo Castle as the "Koka Gumi".

Summary & Bibliography 後書き[edit]

Despite their relatively small size and the wealth of other magnificent castles around Shiga, the Koka castles should not be overlooked by castle explorers. I hope I have been able to convey some of my interest in these sites and maybe catch your interest too. Finally, I owe a big thanks to RaymondW and his wife who first lured me into the Koka region and trapped me in the depths of Koka history while accompanying me on most of these visits. I ran out of time this season, but I have another nice long list of Koka castles to visit next year and hope to see you again.

There is not much quality information on the internet about these sites. I did a lot of research (including trips to the library!) to dig into the sources below. This article is copyright by Jcastle.info. Please do not reproduce without permission.

甲賀市史 v. VII
近畿の城郭
近畿の名城を歩く
近江の平城
近江の山城